Progeny Testing

The Progeny testing method is commonly used in animal breeding programs, and to some extent, in plant breeding. Progeny testing in animals relies on the phenotypic assessment of an individual offspring to make decisions regarding genetic selection. For trades with high heritability, a more straightforward selection protocol may be used, such as selection based on individual performances that are the phenotypic selection. Phenotypic assessment of personal merit is often impractical, for example, for sex-limited traits (milk and egg production in cattle and poultry, respectively) or attributes that need the sacrifice of the individual traits. The parents of progeny with higher performance for desired traits are selected for future breeding.

The idea of progeny testing in animals is not new; Robert Bakewell is reported to have used progeny testing in the 18th century on bulls and rams (male sheep). With the increase in the progeny yield through a given parent, the evaluation also improves. In general, males are selected for progeny testing rather than females because males usually produce more progeny in a given season or year. Their relative importance depends on the heritability of the character.

Progeny Selection 

Progeny selection in animals indicates the choice of breeding (reproducing) stock based on the performance of testing of their offspring or descendant. Family selection refers to the breeding of organisms from the same inherited stock that is not directly related to each other. Additional information about the animals selected includes the animal’s identification name, color, etc.  

Probable Breeding Value (PBV)

The probable breeding value is the calculated genetic dominance of the individual over the group’s average from which it is selected. PBV of the individual for a particular trait may be estimated by,

   PBV= P1+ b(Pi – P1)  

Where, 

b = regression coefficient

Pi = phenotypic value of individual selected

P1 = phenotypic average of individual coeval

Uses of Progeny Testing

As Genetic Resource: The feature of progeny testing is to improve effective heritability. The heritability of family will increase with the number of individuals per family; however, the number of parents will be limited by the number of selections made from preceding generations. Therefore, the genetic growth accomplished in multiple practical projects of the young parental program is identical to what is being achieved under classical progeny testing programs or even better than that.

Exploring Climatic Resilience for Food and Income Crops:  Breeding for the target environment involves testing offspring from different crosses in the required environment in which they are intended to be grown. The vulnerability of progeny could be in the natural environment or mock environment. The progenies, which endure extreme weather, are selected for further evaluation. For example, cassava plants can survive longer in drought areas. During insufficient water, plants lose all their leaves, thereby suspending production. When moisture is patched, then the plants regenerate with minimal loss in output. This capability of cassava to outlive in dry conditions provides it with an edge as a crop in extreme weather in the South African regions.

Advantages of Progeny Testing

• It can be used for sex-limited characters like milk production and slaughter (butcher) traits in meat animals with low heritability.     
• Progeny testing in animals helps prove whether a female parent is free from recessive genes or not.
• Progeny testing in animals also helps in increasing the accuracy of selection. 
• It increases the generation interval.
• It determines the actual breeding value of an animal (mainly male), used extensively to distribute the best germ cells.
• This method is straightforward and suitable.

Limitations of Progeny Testing

• Progeny testing must be done on more animals. It prolongs the generation interval.
• Progeny testing in animals is a time-consuming and expensive process.
• The main disadvantage of progeny selection in plant breeding programs is no control over pollination. 
• The plants of inferior offspring also pollinate the plants of superior offspring. If the germplasm of each plant is tested separately, it would require a lot of areas, which is not practically possible.

Conclusion

Progeny testing is a method commonly used in animal breeding programs and plant breeding. The progeny testing method of selection is widely used in livestock improvement. In progeny testing, the selection of potential parents (usually males) is based on the average performance of an offspring. The mating of the selected parents is planned following this testing method,  to produce a second batch of progeny. These are the next generation of potential parents.